Ruckstell Bearing/Bronze Plate (P211/P139) Fit

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Dan B
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Ruckstell Bearing/Bronze Plate (P211/P139) Fit

Post by Dan B » Mon Jul 20, 2020 11:41 am

I have a brand new P211 thrust bearing and a brand new P139 bronze plate. I pressed the bearing onto the bronze plate as described in the MTFCA Ruckstell book. It went on fairly easily in what I would describe as a light press fit.

Yesterday, I was performing the shift lock function test. When I was removing all of the parts, I set the bearing/bronze plate assembly face down on my work bench. When I went to lift it up, to my surprise the whole bearing slipped right off and laid right there on the bench.

I am confident that the bearing was fully seated. The only thing I can figure is that the cooler temperature in my garage caused a contraction of the materials and allowed them to separate.

How tight of a fit should the bearing be on the bronze plate? Should I consider using Loctite bearing retainer on the surface between the bronze plate and the inner race?

Any thoughts or experience would be helpful.
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Re: Ruckstell Bearing/Bronze Plate (P211/P139) Fit

Post by Dan McEachern » Mon Jul 20, 2020 12:06 pm

Yes it should be a press fit- about .002" interference.


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Re: Ruckstell Bearing/Bronze Plate (P211/P139) Fit

Post by Original Smith » Mon Jul 20, 2020 9:34 pm

When pressing on that bearing, be sure to support the plate with another Ruckstell plate, or you will cave it in.


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Re: Ruckstell Bearing/Bronze Plate (P211/P139) Fit

Post by Willie R » Tue Jul 21, 2020 12:37 pm

Was your new ball bearing made in the USA or a Chinese knock off ?

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Re: Ruckstell Bearing/Bronze Plate (P211/P139) Fit

Post by Dan B » Tue Jul 21, 2020 3:03 pm

The bearing was purchased from one of the major Model T parts suppliers. It is not marked with the country of origin.

Here is the spec sheet for a 7212 angular thrust bearing:

https://www.skf.com/group/products/roll ... 12%20BECBP

This specifies that the inner diameter of the inner race is 60mm which is 2.362” (subject to tolerances).

The Ruckstell book states that the shoulder of the bronze plate should be 2.3625”. Mine measures nominally that much although I am just using a dial calipers.

This seems to me that if you have two parts that are machined perfect that you would only have 0.0005” interference fit.

This does not seem like much and so I guess what I’m asking is that assuming the parts are not perfect, is what I experienced out of the ordinary and should I be taking steps like using loctite bearing retainer to make sure that the inner race stays put once installed.
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Re: Ruckstell Bearing/Bronze Plate (P211/P139) Fit

Post by John M Maslack » Tue Jul 21, 2020 11:08 pm

I rebuilt a Ruckstell where the babbit thrust had failed in it. Some chunks of babbit had wedged it the large bearing and caused it to seize and move on the bronze plate. There was just enough wear so that it was no longer a press fit. It was fixed with a new bronze plate from Chaffins...John

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Re: Ruckstell Bearing/Bronze Plate (P211/P139) Fit

Post by Mark Gregush » Tue Jul 21, 2020 11:18 pm

He has the new bronze plate.
I know the voices aren't real but damn they have some good ideas! :shock:

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Re: Ruckstell Bearing/Bronze Plate (P211/P139) Fit

Post by Dan B » Wed Jul 22, 2020 8:59 am

Thanks Mark.

Anyone want to tell me what they had for lunch yesterday?
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Re: Ruckstell Bearing/Bronze Plate (P211/P139) Fit

Post by Willie R » Mon Aug 03, 2020 9:58 am

I got one of the new Ruckstell ball thrust bearings from a T vendor recently that fits loose as well. The only made in CHINA part on my T. The bearings pictured on all the vendor websites are marked MADE IN THE USA but that's not what you get.
I am thinking of tearing apart my new Ruckstell to get that week link out of there.


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Re: Ruckstell Bearing/Bronze Plate (P211/P139) Fit

Post by StanHowe » Mon Aug 03, 2020 11:53 am

I must be out of the loop if there are some C H Ina made Ruckstell parts around.
I've installed a lot of new bronze plates over the years and every one fit right if you have the correct bearing.
I don't use the offshore bearing, I use US SKF becby angular thrust.
All bearings are measured and sold in metric measurement.
Inner - outer -- width.
A correct bearing is thus a 22-70-18 if my failing memory serves me right. Those are millimeters.


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Re: Ruckstell Bearing/Bronze Plate (P211/P139) Fit

Post by Art Wilson » Mon Aug 03, 2020 10:24 pm

Out of curiosity I would like to know what the bearing inner diameter measurement is using a precision inside micrometer. My suspicion is the bearing is within tolerance.

Since the Ruckstell bronze part is relatively soft, it is easy to form it under size if the bearing tilts ever so slightly while being pressed on. Also the bearing could have a sharp edge at the end where radius meets the bore, which could shave the bronze. So the part may have been to size originally, but now it is under-size.

I would use some Locktite green bearing retainer to secure the bearing. Clean the mating surfaces with Acetone first

If you want to go American for the bearing, EBAY has a number of new USA branded 7212 bearings for sale at reasonable prices. The Japanese Nachi brand bearings are also very good.

Check each part for fit and movement as you assemble the rear end. One of our club members had trouble with some parts being worn to the point that it could not shift all the way into gear once it was all together.


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Re: Ruckstell Bearing/Bronze Plate (P211/P139) Fit

Post by Kbillet » Mon Aug 03, 2020 10:33 pm

Nachi is the better source. There is no guarantee that US named companies are selling US made product.


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Re: Ruckstell Bearing/Bronze Plate (P211/P139) Fit

Post by StanHowe » Tue Aug 04, 2020 1:28 am

The 7212 bearing needs to be becby which designates angular thrust. The 7212 is size nomenclature.
I have bought probably 40 or more SKF bearings. I have no doubt they are US made.
Others..... Hard to say.

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Re: Ruckstell Bearing/Bronze Plate (P211/P139) Fit

Post by Dan B » Wed Aug 12, 2020 8:38 pm

Ok, I've finally had a chance to get caught up and do some research. I'm by no means a bearing expert. Everything I've typed below can be found on the internet, but here it is all in one place:

1. 7212 is a industry designation for a single-row angular contact (thrust) ball bearing. It describes the critical dimensions of the inner and outer races. I have to believe this is why the MTFCA Ruckstell book only says to use a 7212 bearing and says nothing else about a longer part number.

2. The bearing that I received from Lang's is a 7212 ACYGA. The "ACYGA" is a designation system used by SKF and its subsidiaries to describe bearing construction. Therefore I have to believe that what I have is a SKF bearing regardless of where its made.

3. Angular contact bearings are designed with different contact angles. The contact angle describes the point of contact between the balls and the races relative to the operating axis of the bearing. The larger the contact angle, the higher the axial load capability. The smaller the contact angle, the higher the permissible speed capability. Centrifugal force changes the contact angle between the inner and outer race.

4. A "BECBY" bearing has a 40deg contact angle. An "ACYGA" bearing has a 25deg contact angle. Here are the advantages of this bearing taken directly from the SKF website:

AC Series 25deg contact angle bearings:
-have a raceway geometry optimized for high speeds
-have reduced sensitivity to axial loading and misalignment, including the ability to accommodate two times higher peak loads before edge stresses can occur
-are equipped with an optimized machined brass cage as standard

Compared with bearings with 40° contact angle, benefits include:
-20% higher limiting speeds
-higher radial load carrying capacity (by trading off lower axial load carrying capacity)
-increased robustness when used as the backup bearing in sets that are predominantly loaded in one direction


A review of bearing data from the SKF website shows that an "AC" bearing exceeds the basic load ratings of a "BE" bearing, with a 3500r/min increase in the limiting speed rating.

I have to believe that someone at Lang's or other suppliers did a similar analysis and determined that the bearing which I received was better suited for this application which my amateur research seems to support.


Finally, I will say that apparently the information I posted above about there being only a 0.0005" interference fit between two perfect parts is correct since no one has told me otherwise. I know that my parts are not perfect so I decided to use Loctite bearing and sleeve retainer on the surface between the inner race and thrust plate shoulder which is designed for that exact purpose. Unfortunately, you never do things as good the second time around and like a dummy I forgot to buck it with the P145 thrust plate when pressing it back on. So I spent the following hour pressing it back into shape very carefully to achieve less than 0.003" runout. Not perfect but the book says to look for detectable wobble so I would consider this sufficient.

Any comments, questions, speculations or insults are welcome!
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Re: Ruckstell Bearing/Bronze Plate (P211/P139) Fit

Post by StanHowe » Thu Aug 13, 2020 4:33 pm

In my opinion a Ruckstell bearing will never turn fast enough that speed capacity is of any consequence.
Thrust capacity is.

Mounting is
critical.

Some bearings are marked, some not.
I certainly haven't seen them all but the thrust is taken by the flanged side of the bearing so it needs to be positioned away from the plate..


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Re: Ruckstell Bearing/Bronze Plate (P211/P139) Fit

Post by StanHowe » Thu Aug 13, 2020 8:16 pm

Considering that a stock T with a T engine will probably be turning 2500 rpm at maximum and is running stock gears in the rear end maximum RPM for the differential is well under 800 rpm at top speed I don't think there is much necessity for a "high speed" bearing.
Ball bearing speeds of over 6,000 rpm continuous duty may begin to develop centrifugal force and angular contact concerns but I can't imagine any concerns in a model t rear end.

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Re: Ruckstell Bearing/Bronze Plate (P211/P139) Fit

Post by Dan B » Thu Aug 13, 2020 8:21 pm

I’ve got to agree with you there. It might have nothing to do with why I got the bearing I did but it’s helpful to know the how’s and why’s behind the bearing designation if you’re out there searching in the wild for one. The SKF website is a great resource.
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Re: Ruckstell Bearing/Bronze Plate (P211/P139) Fit

Post by StanHowe » Thu Aug 13, 2020 9:14 pm

I doubt that anybody at Lang's could tell you the difference.
I've rebuilt over 70 ruckstells and have seen some pretty strange bearings in them.
Lots of guys are if it fits use it!

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